1. Field of the Invention
This invention relates generally to testing equipment for microprocessor based circuitry. More particularly this invention relates to equipment for automatically testing and assisting in the manual testing of certain microprocessor based circuitry where the circuit under test includes a microprocessor, a read only memory (ROM), and a communication bus.
2. Description of the Prior Art
Previously, test equipment has separated into two principal types in plant equipment for use in manufacturing and field service equipment Previously proposed systems for in plant use involve removal of the microprocessor and replacement with a connector from a computerized test set. An example of this system is shown in U.S. Pat. No. 4,405,054 and U.S. Pat. No. 4,622,647. Field service has principally used switches and displays provided on a maintenance panel and, accordingly, this was limited to large computer systems. Computer controlled testing of an isolated microprocessor clip has been proposed for field service testing (U.S. Pat. No. 4,308,615). This system uses a microprocessor based control to execute instructions carried in its memory and thereby perform operations on the microprocessor chip under test.